Donitra Henderson was gunned down in front of her son, authorities said.

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Oakland police asked for the community's help Thursday in finding the killers of a 21-year-old woman who was fatally shot in North Oakland two years ago as her 4-year-old son watched from the back seat of her car.

Donitra Henderson was visiting friends when she was shot as she was getting out of her car near the corner of 54th Street and Shattuck Avenue at about 8:45 p.m. on April 24, 2013, Lt. Roland Holmgren said.

"She was met by an armed gunman who shot her in front of her son," Holmgren said.

Oakland police and Crime Stoppers are offering a reward of up to $20,000 for information that leads to an arrest and conviction in the case, police spokeswoman Johnna Watson said.

Holmgren said investigators believe the shooting was "not random" and "may have been relationship-based" but didn't provide further details.

Joining police at a news conference at police headquarters, Henderson's mother, Anitra Bishop, said, "I'm asking for the public's help to bring my daughter's murderer to justice." Bishop said Henderson "was a good person who wasn't into any kind of trouble so that makes this all the more tragic because she didn't deserve to die."